This invention relates to a retaining spring for a brake shoe, including a backing plate and a friction pad, of a spot-type disc brake, in particular for automotive vechicles, with a spring leg extending in a tangential direction along a lateral surface of the backing plate, the spring leg having ends which, radially outwardly in relation to the brake disc, are in resilient abutting engagement with guide elements detachably connected with the brake, and with at least one saddle extending from the spring leg and embracing the radial outer edge of the backing plate and resting on the front surface of the backing plate.
The use of retaining springs for the brake shoes of spot-type disc brakes is necessary in order to resiliently clamp the brake shoes in their guides in the brake housing to prevent them from vibrating as a result of shocks and avoid rattling noise in the released state of the brake. Further, the retaining springs prevent automatic movement of the brake shoes in the direction of the brake disc when the brake is released, thus avoiding rubbing contact with the brake disc.
A retaining spring of this type is known from the German Printed Specification No. Dt-OS 2,262,695. The leg of this spring abuts against the lateral surface of the backing plate on the side close to the brake disc and engages with each of its two ends underneath a guide pin which is detachably fixed in the brake housing and extends through an opening in the backing plate in order to guide the latter slidably parallel to the brake-disc axis. The central section of the spring leg is formed by two saddles bent in the form of a U and embracing the radial outwardly directed edge of the backing plate, the saddles being connected with each other by a bridge resting against the lateral surface of the backing plate which is remote from the brake disc. This known retaining spring has the disadvantage of tending to twist the radial inner end of the brake shoe in the direction of brake release so that an excessive brake clearance may occur between the brake shoe and the brake disc when the resistance of the brake actuating members is insufficient with the brake released. The undesired result in an excessive actuating travel when the brake is applied again.